Valeri was signed as a teenager by Italian giants Inter Milan. He was loaned out to various clubs in Italy to gain further experience, including Grosseto. He joined Grosseto permanently in June 2007. In January 2010 Valeri joined Sassuolo. Representing Australia in the starting 11 for the 2010 World Cup is his greatest achievement to date. In May 2013, Valeri and his club Sassuolo finished as Serie B champions, thus securing automatic promotion to Serie Afor the first time in their history. In January 2014, he returned to Serie B with relegation battling Ternana until 30 June in hopes of securing a World Cup place with the Socceroos In June 2014, Carl Valeri returned to his home country signing a 3-year deal with Melbourne Victory. Valeri was an integral part of Victory's 2015 Championship team, starting all 29 games that season. In September 2015 he was appointed captain of the team. Following an interrupted 2015/16 season, Valeri bounced back and became a regular starter for Victory in both the 2016/17 and 2017/18 seasons. In April 2019, Valeri announced that he would retire at the conclusion of the 2018–19 A-League season. In May 2019, it was announced that Valeri had signed on for National Premier Leagues Victoria side Dandenong City, along with former A-League players Adrian Leijer and Brendon Santalab.
International career
Valeri has played for Australia at all international youth levels; Under-17, Under-20 and Under-23. He captained the Australian Under-17 team, the 'Joeys', at the 2001 FIFA World Youth Championship and competed with the Under-23 squad, the 'Olyroos', at the 2004 Athens Olympics. After being an unused substitute in an 2007 Asian Cup qualifier against Bahrain in 2006, the 22-year-old received his second call up to the senior Australian national team in March 2007, as a replacement for the injured defensive midfielder Vince Grella. He made his international debut on 24 March 2007 in a friendly game against China, which Australia won 2–0. This made him the 501st player to be capped for Australia. He made his home debut in a friendly against Uruguay. Former Socceroos coach Graham Arnold has described Valeri as a key player of the future, and possible successor to Grella. This led to certain sections of the Australian media dubbing him "Mini Vinnie."